Electric power system

ABSTRACT

An electric power system in which a plurality of electric power suppliers and demanders are mutually connected via control devices is self-sustainable but also capable of coexisting with the known electric power system. Suppliers/demanders  11  to  15  are mutually connected via an electric power supply and demand line W and have power generation devices  101  and  151 , electrical storage devices  102  and  152 , a plurality of loads  103 , and electric power supply and demand control devices  104  and  153  that detect an electricity shortage or surplus, receives or delivers electric power from or to other suppliers/demanders  12  to  15  accordingly, and automatically or manually controls the power generation devices including a co-gene in respective suppliers/demanders on the basis of a weather forecast, demand prediction, and the like.

TECHNICAL FIELD

The present invention relates to an electric power system in which a plurality of electric power suppliers and demanders are mutually connected by electric power supply and demand control devices.

BACKGROUND ART

In a known electric power system, as shown in FIG. 9, “radial system,” in which a large-scale power plant 91 is a top and demanders 92 are a base, is fundamental. In FIG. 9, in order to ensure a plurality of transmission systems, a “loop system” is introduced in some part. This kind of electric power system is configured, as a single system, in a broad area (for example, several tens of thousands km²) and large scale (several tens GW).

On the other hand, in recent years, a distributed power generation system of a system collaborative type (for example, refer to Patent Document 1) with solar generation and a fuel cell has been focused. The distributed power generation system of the system collaborative type is usually built in an end region or a local region near the end of the known radiated electric power system, and is premised on interconnection with the electric power system.

-   Patent document 1: Japanese Patent Application Laid-Open No.     6-327146

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

In the known electric power system structure shown in FIG. 9, since transportation of electric power is massively carried out over a long distance, there are a lot of losses; and in electric generation come from reproducible energy such as solar energy and wind power energy, since its reproducible energy is ubiquitous, it is difficult to build a large scale power plant using these energies.

An object of the present invention is to provide an electric power system in which a plurality of electric power suppliers and demanders who demand electric power and also supply electric power are configured by being mutually connected by electric power supply and demand control devices, the electric power system being self-sustainable without depending on the known electric power system. This does not intend that the system of the present invention eliminates coexisting with the known electric power system.

Means for Solving the Problems

According to a first configuration of the present invention to solve the above problem, there is provided an electric power system in which a plurality of electric power suppliers and demanders (in the drawings, it is described as Unit to supply and demand electric power) are mutually connected, the electric power supplier and demander being provided with one or a plurality of power generation devices, one or a plurality of electrical storage devices and one or a plurality of electric power consumption devices, and an electric power supply and demand control device.

In the electric power system, each of the electric power supply and demand control devices determines whether or not electric power shortage is occurred or whether or not electric power surplus is occurred in each of the electric power suppliers and demanders provided with the electric power supply and demand control device, receives electric power from other electric power supplier and demander provided with the power generation device and/or the electrical storage device in the case where electric power shortage is occurred in the electric power supplier and demander, controls to deliver electric power to other electric power supplier and demander in the case where electric power surplus is occurred in the electric power supplier and demander, and automatically or manually controls the plurality of the power generation devices in respective power suppliers and demanders on the basis of weather forecast, electric power demand prediction, heat demand prediction, setting values by each supplier and demander, and the like in the delivery and receipt of electric power.

Furthermore, according to a second configuration of an electric power system of the present invention, there is provided an electric power system in which a plurality of electric power suppliers and demanders are mutually connected, the electric power supplier and demander being provided with at least one device selected from one or a plurality of power generation devices, one or a plurality of electrical storage devices and one or a plurality of electric power consumption devices, and an electric power supply and demand control device.

In the electric power system, the plurality of the electric power suppliers and demanders are sectioned into a plurality of groups, and

the electric power supply and demand control device which belongs to each group determines whether or not electric power shortage is occurred or whether or not electric power surplus is occurred in the group, receives electric power from other group to which the electric power supplier and demander provided with the power generation device and/or the electrical storage device belongs in the case where electric power shortage is occurred in the group and, delivers electric power to other group in the case where electric power surplus is occurred in the group, and automatically or manually controls the plurality of the power generation devices in respective power suppliers and demanders of respective groups on the basis of weather forecast, electric power demand prediction, heat demand prediction, and the like in the delivery and receipt of electric power.

Each electric power supplier and demander of the electric power system of the present invention refers to information from the electric power supply and demand control device in other electric power supplier and demander and can set or change operating conditions of the electric power supply and demand control device of the electric power supplier and demander on the basis of the amount of electric power consumption which is estimated by the electric power supplier and demander.

Furthermore, in the electric power system of the present invention, the electrical storage device in the electric power supplier and demander can use a storage battery and an electric double layer capacitor together.

In this case, it is preferable to quantitatively comprehend a change in the amount of electrical storage of the storage battery and its charge and discharge transient operation characteristics. This can properly comprehend and analyze charge and discharge phenomena of the storage battery and the electric double layer capacitor.

When the amount of electrical storage of the storage battery is detected, the amount of charge and discharge can be controlled so that its detected value is not to be less than a predetermined lower limit; accordingly, transient response characteristics of the capacitor can be utilized without involving unnecessary consumption of the storage battery.

Further, in the present invention, although not shown in the drawing, a movable power generation device and/or a movable electrical storage device provided by any electric power supplier are/is moved to other electric power supplier and delivery and receipt of necessary electric power can be performed there.

Effect of the Invention

The present invention is an electric power system in which a known electric power system is not provided and each electric power supplier and demander is basically independent. That is, each electric power supplier and demander performs sending and receiving (also referred to as delivery and receipt, hereinafter, same as above) of electric power with other electric power suppliers and demanders when electric power shortage or electric power surplus is occurred. Accordingly, it becomes possible to achieve independence in the whole system in which respective electric power suppliers and demanders are coupled by an electric power network.

In the present invention, a plurality of the electric power suppliers and demanders can be connected to a branched electric power supply and demand line, a beaded electric power supply and demand line, a radiated electric power supply and demand line, a net shaped electric power supply and demand line, or an electric power supply and demand line combined by these lines (hereinafter, the before mentioned each line is also referred to as an electric power supply and demand network in the present invention).

Furthermore, in the present invention, the before mentioned electric power supply and demand control device can perform exchange of supply and demand information of electric power with the electric power supply and demand control devices of other electric power suppliers and demanders via a data communication network.

In the present invention, a plurality of the electric power suppliers and demanders can be connected in DC with each other in order to sufficiently utilize advantage of DC electrical transmission and distribution.

Further, in the present invention, if delivery and receipt of electric power among respective electric power suppliers are made by moving movably provided power generation devices and/or electrical storage devices, connection among respective suppliers and demanders of electric power can be simplified.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an explanation diagram showing an embodiment of an electric power system of the present invention;

FIG. 2 is a block diagram exemplifying a configuration of one electric power supplier and demander and an electric power supply and demand control device thereof;

FIG. 3 is an explanation diagram at a time when an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of AC electric power with other electric power supplier and demander in an electric power system of the present invention;

FIG. 4 is an explanation diagram at a time when an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of DC electric power with other electric power supplier and demander in an electric power system of the present invention:

FIG. 5 is an explanation diagram in the case of supplying DC electric power to a load via house wiring of an electric power supplier and demander in an electric power system of the present invention;

FIG. 6 is an explanation diagram showing a state where electric power suppliers and demanders are hierarchized in an electric power system of the present invention;

FIG. 7(A) is an explanation diagram in the case where electric power suppliers and demanders are connected in a branched shape; FIG. 7(B) is an explanation diagram in the case where the electric power suppliers and demanders are connected in a star shape; and FIG. 7(C) is an explanation diagram in the case where the electric power suppliers and demanders are connected in a net shape;

FIG. 8 is a diagram showing an example of an electric power supplier and demander connected via an electric power supply and demand line which is different from a plurality of other electric power suppliers and demanders; and

FIG. 9 is an explanation diagram showing a known electric power system.

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 is an explanation diagram showing an embodiment of an electric power system of the present invention; FIG. 2 is a block diagram exemplifying a configuration of one electric power supplier and demander and an electric power supply and demand control device thereof; FIG. 3 is an explanation diagram at a time when an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of AC electric power with other electric power supplier and demander in an electric power system of the present invention; FIG. 4 is an explanation diagram at a time when an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of DC electric power with other electric power supplier and demander in an electric power system of the present invention; FIG. 5 is an explanation diagram in the case of supplying DC electric power to a load via house wiring of an electric power supplier and demander in an electric power system of the present invention; FIG. 6 is an explanation diagram showing a state where electric power suppliers and demanders are hierarchized in an electric power system of the present invention; FIG. 7(A) is an explanation diagram in the case where electric power suppliers and demanders are connected in a branched shape; FIG. 7(B) is an explanation diagram in the case where the electric power suppliers and demanders are connected in a star shape; and FIG. 7(C) is an explanation diagram in the case where the electric power suppliers and demanders are connected in a net shape; FIG. 8 is a diagram showing an example of an electric power supplier and demander connected via an electric power supply and demand line which is different from a plurality of other electric power suppliers and demanders; and FIG. 9 is an explanation diagram showing a known electric power system.

An electric power system 1 shown in FIG. 1 shows only electric power suppliers and demanders of a plurality of electric power suppliers and demanders 11 to 15. The respective electric power suppliers and demanders 11 to 15 are mutually connected via an electric power supply and demand line W.

The electric power supplier and demander 11 is provided with a power generation device 101, an electrical storage device 102, a plurality of loads (electrical devices) 103, and an electric power supply and demand control device 104. Incidentally, a plurality of electrical devices 103 are shown by A1, A2, . . . , An. Furthermore, in FIG. 1, other electric power suppliers and demanders 12, 13, and 14 and other electric power supplier and demander (not shown in the drawing) are also provided with a power generation device, an electrical storage device, a plurality of loads (electrical devices), and an electric power supply and demand control device as in the electric power supplier and demander 11; and, each device is connected to branched shape house wiring. Incidentally, there is also a case where all the respective electric power suppliers and demanders or arbitrary electric power suppliers and demanders mount the power generation device 101 and/or the electrical storage device 102 on a pallet of a truck or the like or provide them in a mountable manner, and deliver the power generation device 101 and/or the electrical storage device 102 to other electric power suppliers and demanders as needed; and delivery and receipt of electric power is performed there.

In the present invention, the respective electric power suppliers and demanders are loosely coupled thereamong. That is, each of the electric power suppliers and demanders is basically of an independent type, can receive electric power from other electric power supplier and demander when electric power shortage is occurred, and can supply electric power to other electric power supplier and demander when electric power surplus is occurred.

The electric power supplier and demander 11 is, for example, general houses, multiple dwelling houses, small, medium, and large scale factories, low-rise, medium-rise, and high-rise buildings and the like. Further, a group in which these general houses and multiple dwelling houses are collected can also serve as the electric power supplier and demander 11 of the present invention.

Typically, the power generation device 101 is a solar generator and a DC power supply such as a fuel cell or the like. There is also a case where wind generation, biomass generation, or a co-generation system (hereinafter, referred to as co-gene in this description) such as a gas engine system, a gas turbine system, a fuel cell system, and the like is used as the power generation device 101. A wind generation device, a biomass generation device, and the co-gene usually serve as an AC power supply; however, its output is AC/DC converted and can be used as a DC power supply. In addition, the electrical storage device 102 serves as a DC power supply.

Further, although not shown in the drawing, a flywheel unit can also be used for the power generation device 101. The flywheel unit can also be used for the electrical storage device 102. Furthermore, an electrical storage device combined by a storage battery and an electric double layer capacitor is also included. There is a case where the power generation device 101 and/or the electrical storage device 102 are/is mounted on a truck pallet or the like and moved to other electric power supplier, and delivery and receipt of electric power is performed there. The load 103 is, for example, a DC device or an AC device, such as an electric light, an air conditioner, a refrigerator, an electromagnetic cooking device, a rice cooker, and the like.

As shown in FIG. 2, by way of example, the electric power supply and demand control device 104 has a control unit 104 b which detects a time when electric power surplus is occurred in the electric power supplier and demander 11, for example, a time when the amount of electric power use of the load 103 is reduced and the electrical storage device 102 is near full charge or full charge and can supply electric power generated by the power generation device 101 from an electric power sending and receiving unit 104 a to other electric power supplier and demander or the electric power supplier and demander 15, which is connected to the electric power supply and demand line W. There is also a case where this supply of electric power is performed by movement of the power generation device 101 or movement of the electrical storage device 102 without using the electric power supply and demand line W. Furthermore, the electric power supply and demand control device 104 has the control unit 104 b which detects a time when electric power shortage is occurred in the electric power supplier and demander 11, for example, a time when the amount of electric power use of the load 103 is rapidly increased. Then, the electric power supply and demand control device 104 has the electric power sending and receiving unit 104 a which receives electric power via the electric power supply and demand control devices of other electric power suppliers and demanders 12, 13, and 14 in which electric power surplus is occurred, the electric power suppliers and demanders being connected to the electric power supply and demand line W, or via an electric power supply and demand control device 153 (to be described later) of the electric power supplier and demander 15 and can drive the load 103 through control of the control unit 104 b, or can store in the electrical storage device 102.

The electric power supplier and demander 15 includes a power generation device 151, an electrical storage device 152, and the electric power supply and demand control device 153. Incidentally, the electric power supplier and demander can include only either the power generation device or the electrical storage device. The power generation device 151 is typically a middle scale facility for thermal power, hydraulic power, wind power and the like including a co-gene and a biomass generation facility; and the electrical storage device 152 is typically a secondary battery; however, there is also one which is combined by the storage battery (secondary battery) and the electric double layer capacitor. The electric power supplier and demander 15 can supply electric power to the electric power supplier and demander 11 (or, other electric power suppliers and demanders 12 to 14 and the like) as described above via the electric power supply and demand control device 153. Furthermore, conversely, the electric power supplier and demander 15 can receive supply of electric power from the electric power supplier and demander 11 (or, other electric power suppliers 12 to 14 and the like). Delivery and receipt of electric power in the electric power supplier and demander 15 is also performed via the electric power supply and demand control device; however, as described before, the delivery and receipt of the electric power may be performed by introducing the movable power generation device and electrical storage device of other electric power supplier and demander to the supplier and demander 15.

Electric power in which the electric power supplier and demander 15 supplies to the electric power supplier and demander 11 and the like is electric power generated by the power generation device 151 or electric power stored in the electrical storage device 152; and electric power in which the electric power supplier and demander 15 is supplied from the electric power supplier and demander 11 and the like is stored in the electrical storage device 152. In the electric power system of the present invention, a plurality of power generation devices including a co-gene and a biomass generator in respective power suppliers and demanders can be controlled both automatically and manually on the basis of weather forecast, electric power demand prediction, values based on heat demand prediction, values set by each electric power supplier and demander, or the like in the delivery and receipt of electric power via the electric power supply and demand control device of each electric power supplier and demander (refer to 104 c shown in FIG. 2). Further, each electric power supplier and demander refers to various information from the electric power supply and demand control device in other electric power supplier and demander and can set or change operating conditions of the electric power supply and demand control device of the electric power supplier and demander on the basis of the amount of electric power consumption which is estimated by the electric power supplier and demander (refer to FIG. 2).

In the above respective power generation devices 101, control may be made individually for each power generation device, for example, a solar generator is controlled by a conditioner; and a fuel cell and a micro generator are controlled by a power conditioner. However, in the electric power system of the present invention, a control element common to each power generation device is overall controlled by the electric power supply and demand control devices 104 and 101 and a control element specific to an individual power generation device is individually controlled; accordingly, the power generation devices 101 and the same 151 in a handful of the electric power supplier and demander 11 and the same 15 can be optimally controlled as a whole.

Incidentally, each power generation device such as a known solar generator and a fuel cell only performs control of full output control and system connection by each power conditioner; however, in the present invention, electric power to be supplied and demanded by utilizing a flywheel unit or the like is equalized between output of each power generation device from zero to full output, so that control can be made freely by the electric power supply and demand control devices 104 and 153.

On the other hand, the above electrical storage devices 102 and 152 typically use a secondary battery independently as a DC power supply. However, in the electric power system of the present invention, the storage battery (secondary battery) and the electric double layer capacitor can be used together for the electrical storage devices 102 and 152.

When the above storage battery and the electric double layer capacitor are used together, for example, control to use depending on electrical storage characteristics and discharge characteristics is controlled by the electric power supply and demand control devices 104 and 153; accordingly, it becomes possible to reasonably respond to diversification of supply and demand mode of electric power in each electric power supplier and demander or diversification of supply mode of electric power in each supplier and demander.

In this case, the storage battery and the electric double layer capacitor are decentrally arranged, for example, the electric double layer capacitor is mounted on the electric power supply and demand control devices 104 and the same 153, and the storage battery is separately disposed or mounted on the electrical device 103; accordingly, a remaining battery level of the electrical storage devices 102 and 152 can be passed to supply according to priority order of electric power demand destinations by way of example.

Further, formerly, various kinds of electrical devices serving as the load 103 provided with the electric power supplier and demander 11 are individually operated by simply individually inputting and cutting off (ON and OFF) electric power.

However, in the electric power system of the present invention, a starting preferential order and the size of starting electric power (descending order, or reverse order thereof) of an individual electrical device such as a refrigerator, an air conditioner, a TV, or the like, which constitutes the load 103 in the electric power supplier and demander 11, are set in the electric power supply and demand control device 104; for example, control is made so as to be an order in which a starting order (or a cutting off order) or an order in which an electromotive force is in a descending order; accordingly, it becomes possible to equalize electric power consumption. Furthermore, when an electrical device with large starting electric power is started, the electric power supply and demand control device 104 can be actuated so that electric power at a time of starting of a device with large starting electric power is supplied from the storage battery provided with the electric double layer capacitor and the flywheel unit.

When electric power consumption can be equalized by controlling priority order at a time of starting as described above, there can be performed dispersion control of an excess current which is easy to flow to the electric power supply and demand control device 104 and the respective electrical devices 103 at a time of starting of the respective electrical devices 103; therefore, there can be prolonged duration of life of the control device 104 itself, the respective electrical devices, or wiring components such as wiring for connecting therebetween.

In addition, control can be made so as not to cause a large pulsation in which current becomes maximum or minimum by the electric power supply and demand control device 104; therefore, it is useful for ensuring more stable operation of the electric power supply and demand control device 104 and the individual electrical device 103.

Further, for example, the elimination of a TV standby state and a standby operation of other device can be achieved by changing the electric power supply and demand control device 104 and applied electric power to DC, and therefore, unnecessary electric power consumption can be suppressed.

In the electric power system shown in FIG. 1, in the case where the electric power supply and demand control device 104 performs supply and demand of electric power with other electric power suppliers and demanders 12 to 15, the electric power supply and demand control device 104 exchanges information with electric power supply and demand control devices of the other electric power suppliers and demanders and determines supply and demand conditions or the like.

In the electric power system shown in FIG. 1, the supply and demand of electric power among the electric power suppliers and demanders can be performed by AC or can be performed by DC; however, in either case, construction can be made as a local electric power system or construction can be made as a large electric power system in which these electric power systems are combined.

In the electric power system shown in FIG. 1, although not shown in the drawing, there is also a case where the electric power supplier and demander made up of only loads is connected to the electric power supply and demand line W. Furthermore, in the electric power system shown in FIG. 1, equalization of supply and demand electric power is performed by mutually connecting many and various electric power suppliers and demanders.

In the case where the electrical storage device 102 of the electric power supplier and demander 11 is large capacity, and when it is high cost, it becomes possible to purvey the loads by electric power to be supplied from other electric power supplier and demander by using small capacity as the electrical storage device 102 (or, not being provided with the electrical storage device 102). In this case, it is preferable that electric power suppliers and demanders different in time slot electric power consumption pattern (for example, houses and business establishments) exist together in the electric power system 1. Furthermore, it is preferable that those different in electric generation mode (for example, a solar generation device, a wind generation device, and a biomass generation device) as the electric power supplier and demander 15 exist together.

FIG. 3 is an explanation diagram showing electric power system in which an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of AC electric power with other electric power supplier and demander.

Electric power suppliers and demanders 11 a, 12 a, 13 a, 14 a, and 15 a shown in FIG. 3 correspond to the electric power suppliers and demanders 11, 12, 13, 14, and 15 shown in FIG. 1. An electric power supply and demand control device 51 of the electric power supplier and demander 11 a shown in FIG. 3 includes a control device 511 and a bidirectional AC/DC converter 512.

Control devices of the respective electric power suppliers and demanders are configured so as to be able to perform data communication by a communication line CL, and can exchange supply and demand information in the case of the electric power supply and demand.

Furthermore, an electric power supply and demand control device 61 of the electric power supplier and demander 15 a includes a control device 611, and a bi-directional AC/AC or DC/AC converter 612. When the supply and demand of AC electric power is performed between the electric power suppliers and demanders, voltage, current, frequency, and phase have to be matched between both the electric power suppliers and demanders. This matching is performed by the electric power supply and demand control devices 51 and 61. Incidentally, in FIG. 3, although not shown in the drawing, the electric power supply and demand control devices 51 and 61 can further include a circuit breaker, a current limiter, a watt-hour meter, and the like. In addition, in the electric power supplier and demander provided with the watt-hour meter and a capacitor, the control devices 51 and 61 control discharge; and in the electric power supplier and demander provided with a photovoltaic cell, there is provided with a conditioner which takes out the maximum electric power from a nonlinear electromotive force and adjusts to electric power of the rated characteristics.

FIG. 4 is an explanation diagram showing electric power system in which an electric power supply and demand control device of an electric power supplier and demander performs supply and demand of DC electric power with other electric power supplier and demander.

Electric power suppliers and demanders 11 b, 12 b, 13 b, 14 b, and 15 b shown in FIG. 4 correspond to the electric power suppliers and demanders 11, 12, 13, 14 and 15 shown in FIG. 1. An electric power supply and demand control device 71 of the electric power supplier and demander 15 b shown in FIG. 4 includes a control device 711 and a bi-directional DC/DC converter 712.

Control devices of the respective electric power suppliers and demanders are configured so as to be able to perform data communication by a communication line CL, and can exchange supply and demand information in the case of the electric power supply and demand.

Furthermore, an electric power supply and demand control device 81 of the electric power supplier and demander 15 b includes a control device 811, and a bi-directional DC/DC or DC/AC converter 812. When the supply and demand of electric power in DC is performed between the electric power suppliers and demanders, adjustment of voltage and current is performed. Incidentally, in FIG. 4, although not shown in the drawing, the electric power supply and demand control devices 71 and 81 can further include a current limiter, a watt-hour meter, and the like. In addition, in the electric power suppliers and demanders provided with the watt-hour meter and a capacitor, their control devices 71 and 81 control charge/discharge; and in the electric power supplier and demander provided with a photovoltaic cell, there is provided with a conditioner which takes out the maximum electric power from a nonlinear electromotive force and adjusts to electric power of the rated characteristics.

FIG. 5 is an explanation diagram in the case of distributing DC electric power to a load via house wiring of an electric power supplier and demander.

In an electric power supplier and demander 11 c shown in FIG. 5, there is specifically shown the power generation device, the electrical storage device, and a plurality of loads in the electric power supplier and demander 11 shown in FIG. 1. Incidentally, an electric power supply and demand control device 71 shown in FIG. 5 is the same as the electric power supply and demand control device 71 shown in FIG. 4.

In the electric power supplier and demander 11 c, the power generation device is a solar generator 701 by way of example, the electrical storage device is a battery 702, and the plurality of loads are a DC load 7031 and an AC load 7032.

In this case, a bi-directional DC/DC converter 712 performs supply and demand of electric power with the battery 702, the solar generator 701, and the DC load 7031 and performs supply and demand of electric power with the AC load 7032 via a DC/AC converter 706.

Electric power generated by the solar generator 701 is supplied to the battery 702 and the DC load 7031 via, for example, the bi-directional DC/DC converter 712 or supplied to the AC load 7032 via the DC/AC converter 706.

The electric power supply and demand control device 71 includes a function which controls charging of the battery 702 and a function which compensates for stable output to the side of house wiring L.

Electric power from the electric power supply and demand control device 71 is supplied to the DC load 7031 via the house wiring L and the DC outlet 7051. The electric power from the electric power supply and demand control device 71 is supplied to the AC load 7032 via the house wiring L, the DC/AC converter 706A, and the AC outlet 7052. Incidentally, in FIG. 4, the DC outlet and the AC outlet are shown by one outlet, respectively; however, the DC outlet and the AC outlet are provided with a plurality of outlets, respectively, and the DC loads and the AC loads can be connected to those outlets.

In the respective electric power suppliers and demanders 11, 15, and the like in the electric power system of the present invention described above, the electric power supply and demand control devices 104, 153, and the like in which the respective electric power suppliers and demanders 11, 15, and the like include are served as nodes and the electrical feeder line W among the respective electric power suppliers and demanders 11, 15, and the like is served as a link; accordingly, an electric power network is formed. Therefore, the respective electric power supply and demand control devices 104, 153, and the like are provided with a function which controls exchange of electric power among the respective electric power suppliers and demanders 11, 15, and the like.

The fundamental function of the electric power supply and demand control devices 104 and 153 is determination of the electric power suppliers and demanders 11, 15, and the like serving as other parties who perform exchange of electric power; determination of whether the exchange of electric power with the other parties is delivery or intake; control of an electric power rate and an electric energy and the like. This function controls at a high level that connection is made by communication circuits among the electric power networks; data such as necessary electric power and electric power available for supply for mutual electric power suppliers and demanders, an electric energy and an electric power rate thereof, and these related future estimations are exchanged and processed; and electric power among the respective electric power suppliers and demanders is accommodated with each other.

The function of the above electric power supply and demand control devices 104 and 153 serve as a circuit breaker and a current limiter by configuring on the basis of, for example, a voltage converter, a current controller, and a switch, which are provided with various control functions; by individually switching communication channels of necessary electric power by control of the converter or the like; and by being based on the size of a transmission current and characteristic analysis of transient phenomenon. This allows the electric power supply and demand control devices 104 and 153 to control so that, for example, when an electrical fault is occurred in a certain electric power supplier and demander, each electrical device (load 103), electrical storage device 102, and power generation device 101 of the supplier and demander are not completely cut off, but only a necessary line is cut off and other line can be used without cutting off.

By the way, in the electric power system shown in FIG. 1, a properly collected number of groups of the electric power suppliers and demanders can be treated as one electric power supplier and demander. As shown in FIG. 6, electric power supplier and demander groups G11, G12, . . . show a group at this time (for example, approximately several tens to ten thousands of houses).

In FIG. 6, the electric power supplier and demander groups G11, G12, . . . are mutually connected via electric power supply and demand control devices S1. Furthermore, higher hierarchy of the electric power supplier and demander groups G11, G12, . . . are represented by G21, G22, . . . , and further higher hierarchy are represented by G31, G32, G33, . . . . In this case, although not shown in the drawing, further higher hierarchy than G31, G32, G33, . . . are formed.

For example, the electric power supplier and demander groups G11, G12 . . . are set as a “town” unit; G21, G22, . . . are set as a “city” unit; and G31, G32, G33, . . . are set as a “prefecture” unit.

In FIG. 6, the electric power supplier and demander groups G11, G12, . . . are mutually connected with other electric power suppliers and demanders by the electric power supply and demand control devices S1; however, the respective higher hierarchies and lower hierarchies are hierarchically connected with each other via electric power supply and demand control devices S2, S3, S4, . . . .

In the above embodiments, there is described a case where the respective electric power suppliers and demanders are connected in a branched shape as shown in FIG. 7(A). The respective electric power suppliers and demanders may be connected in a star shape as shown in FIG. 7(B) or may be connected in a net shape as shown in FIG. 7(C). Further, the respective electric power suppliers and demanders may be connected in a mode combined with these shapes.

FIG. 8 is a diagram showing an example of an electric power supplier and demander connected via an electric power supply and demand line which is different from a plurality of other electric power suppliers and demanders. In FIG. 8, a bidirectional DC/DC converter 712 transports electric power among the electric power supply and demand lines W1, W2, and W3 and can intermediate electric power supply and demand among other electric power suppliers and demanders, for example, in the connection mode of the electric power suppliers and demanders as shown in FIG. 7(C). The transportation of electric power among the electric power supply and demand lines W1 to W3 includes a mode which supplies and demands electric power by moving a movable power generation device and/or a movable electrical storage device.

Industrial Applicability

According to the present invention, there can be provided an electric power system, in which a plurality of electric power suppliers and demanders are configured by being mutually connected by electric power supply and demand control devices, without depending on the known electric power system.

DESCRIPTION OF REFERENCE NUMERALS

-   -   1 Electric power system

-   11, 12, 13, 14, 11 a, 12 a, 13 a, 14 a, 11 b, 12 b, 13 b, 14 b, 11     c, 11 d, 12 c, 13 c, 14 c, 15, 15 a, and 15 b Electric power     supplier and demander (Unit to supply and demand electric power)

-   51, 61, 71, 81, 104, and 153 Electric power supply and demand     control device

-   101 and 151 Power generation device

-   102 and 152 Electrical storage device

-   103 Load

-   511, 611, 711, and 811 Control device

-   512 Bi-directional AC/DC converter

-   612 Bi-directional AC/AC or DC/AC converter

-   706 DC/AC converter

-   712 Bi-directional DC/DC converter

-   812 Bi-directional DC/DC or DC/AC converter

-   CC Communication line

-   CL Communication line

-   L House wiring

-   W, W1, W2, and W3 Electric power supply and demand line 

The invention claimed is:
 1. A self-sustainable electric power grid, not depending on a large-scale power plant but also capable of coexisting with a known electric power system, comprising: a plurality of supplier/demanders of electric power, mutually connected via an electric power supply and demand line; each supplier/demander comprising one control device; at least one load device; and at least one device selected from the group consisting of electricity power generation devices and electricity storage devices; the control devices including circuitry that determines whether there exists in each respective supplier/demander an electric-power shortage or an electric-power surplus; wherein, in the case where an electric-power surplus is determined, the respective control device delivers electric power to other suppliers/demanders via the electric power supply and demand line; wherein, in the case where an electric-power shortage is determined, the respective control device accepts electric power from other suppliers/demanders via the electric power supply and demand line; wherein delivery and receipt of electric power is performed by moving a movable power generation device and/or a movable electrical storage device to another supplier/demander; and wherein each supplier/demander refers to information from the control device in another supplier/demander, and sets or changes operating conditions of the control device or devices of said each supplier/demander on the basis of the amount of electric power consumption which is estimated by the other supplier/demander.
 2. The electric power system according to claim 1, wherein the plurality of electric power suppliers/demanders are sectioned into a plurality of groups, and wherein a control device which belongs to each group determines whether or not an electric power shortage or an electric power surplus has occurred within the group, receives electric power from another group in the case where electric power shortage has occurred in the group, and delivers electric power to the other group in the case where electric power surplus has occurred in the group, and controls the plurality of the power generation devices in respective suppliers/demanders of respective groups depending on a weather forecast, an electric power demand prediction, a heat demand prediction, or other predictions of delivery and receipt of electric power.
 3. The electric power grid according to claim 2, wherein each of the suppliers/demanders refers to information from the control device in another electric power supplier/demander, and sets or changes operating conditions of the control device of the supplier/demander on the basis of an amount of electric power consumption which is estimated by the supplier/demander.
 4. The electric power grid according to claim 2 or 3, wherein the power generation device of each supplier/demander is such that a control element common to each power generation device is commonly controlled, and a control element specific to an individual power generation device is individually controlled.
 5. The electric power grid according to any one of claims 1, 2, and 3, wherein the power generation device of each of the suppliers/demanders includes at least a co-generation system and a biomass generator.
 6. The electric power grid according to any one of claims 1, 2, and 3, wherein the electrical storage device in each supplier/demander includes a storage battery and an electric double layer capacitor together.
 7. The electric power grid according to any one of claims 1, 2, and 3, wherein the electric power supply and demand line is branched, beaded, radiated, and/or net shaped, and wherein the plurality of suppliers/demanders are connected to the branched electric power supply and demand line, the beaded electric power supply and demand line, the radiated electric power supply and demand line, the net shaped electric power supply and demand line, or the electric power supply and demand line combined with any combination thereof.
 8. The electric power grid according to any one of claims 1, 2, and 3, wherein the control device of each supplier/demander performs exchange of supply and demand information of electric power with the control devices of other suppliers/demanders via a data communication network.
 9. The electric power grid according to any one of claims 1 and 3, wherein the plurality of suppliers/demanders are mutually DC-connected.
 10. The electric power grid according to claim 1, wherein each supplier/demander comprises one respective control device. 